Comment # 5 on bug 1217083 from Takashi Iwai

Hm, then it smells really strange.  In general, the microcode won't be updated
unless it really matches with the CPU (the CPU itself checks).

Since this is the only report -- although it should have hit to far more people
-- I'm afraid that we're scratching the wrong surface.

Could you double-check whether it's really ucode-amd package that really
breaks?
As mentioned, you can control the ucode loading via a boot option (so you can
type in on GRUB menu at boot time).